The formulation of bleaching compositions which effectively remove a wide variety of soils and stains from fabrics under wide-ranging usage conditions remains a considerable challenge to the laundry detergent industry. Challenges are also faced by the formulator of hard surface cleaning compositions and automatic dishwashing detergent compositions (ADD's), which are expected to efficiently cleanse and sanitize dishware, often under heavy soil loads. The challenges associated with the formulation of truly effective cleaning and bleaching compositions have been increased by legislation which limits the use of effective ingredients such as phosphate builders in many regions of the world.
Oxygen bleaching agents, such as hydrogen peroxide, have become increasingly popular in recent years in household and personal care products to facilitate stain and soil removal. Bleaches are particularly desirable for their stain-removing, dingy fabric cleanup, whitening and sanitization properties. Oxygen bleaching agents have found particular acceptance in laundry products such as detergents, in automatic dishwashing products and in hard surface cleaners. Oxygen bleaching agents, however, are somewhat limited in their effectiveness. Some frequently encountered disadvantages include color damage on fabrics and surfaces. In addition, oxygen bleaching agents tend to be extremely temperature rate dependent. Thus, the colder the solution in which they are employed, the less effective the bleaching action. Temperatures in excess of 60.degree. C. are typically required for effectiveness of an oxygen bleaching agent in solution.
To solve the aforementioned temperature rate dependency, a class of compounds known as "bleach activators" has been developed. Bleach activators, typically perhydrolyzable acyl compounds having a leaving group such as oxybenzenesulfonate, react with the active oxygen group, typically hydrogen peroxide or its anion, to form a more effective peroxyacid oxidant. It is the peroxyacid compound which then oxidizes the stained or soiled substrate material. However, bleach activators are also somewhat temperature dependent. Bleach activators are more effective at warm water temperatures of from about 40.degree. C. to about 60.degree. C. In water temperatures of less than about 40.degree. C., the peroxyacid compound loses some of its bleaching effectiveness.
Numerous substances have been disclosed in the art as effective bleach activators. One widely-used bleach activator is tetraacetyl ethylene diamine (TAED). TAED provides effective hydrophilic cleaning especially on beverage stains, but has limited performance on hydrophobic stains, e.g. dingy, yellow stains such as those resulting from body oils. Another type of activator, such as non-anoyloxybenzenesulfonate (NOBS) and other activators which generally comprise long chain alkyl moieties, is hydrophobic in nature and provides excellent performance on dingy stains. However, many of the hydrophobic activators developed demonstrate limited performance on hydrophilic stains.
The search, therefore, continues for more effective activator materials, especially for those which provide satisfactory performance on both hydrophilic and hydrophobic soils and stains. Improved activator materials should be safe, effective, and will preferably be designed to interact with troublesome soils and stains. Various activators have been described in the literature. Many are esoteric and expensive.
It has now been determined that certain selected bleach activators are unexpectedly effective in removing both hydrophilic and hydrophobic soils and stains from fabrics, hard surfaces and dishes. When formulated as described herein, bleach additive and bleaching compositions are provided using the selected bleach activators to remove soils and stains not only from fabrics, but also from dishware in automatic dishwashing compositions, from kitchen and bathroom hard surfaces, and the like, with excellent results.